As is known in the art, phased array antennas (or more simply “phased arrays”) are used in communication, radar, and direction-finding systems as well as in other multifunction radio frequency (RF) systems. Phased arrays are typically provided from many individual radiating antenna elements. The selection of the individual radiating element and arrangement of such elements have significant impact on the performance and cost of the phased array antenna.
As is also known, it is often desirable for the radiating elements to be capable of efficiently transmitting and receiving RF signals having multiple polarizations while at the same time exhibiting a low insertion loss characteristic, over a wide frequency bandwidth and a wide electronic scan volume.
One type of antenna element used to make a phased array antenna is called a tapered slot antenna element (also known as a “notch” antenna element). Notch antenna elements can have a relatively low insertion loss characteristic and can operate over a relatively wide frequency bandwidth and a relatively wide electronic scan volume.
Construction of such tapered slot phased array antennas, however, requires electrical continuity between elements. This makes difficult (and in some cases prohibits) the use of a triangular lattice pattern in a phased array, and also requires the use of feed structures having interconnects which are not disposed on a single plane (i.e. the feed structure is on multiple different layers of a multi-layer printed circuit board). This results in a phased array having a relatively complex physical architecture (e.g. complex feed structures and electronics packaging). Furthermore, the inability to use a triangular lattice combined with a complex feed structure results in increased cost and complexity in phased array antennas provided from notch antenna elements.
As is also known, there are a wide variety of tapered slot antenna designs having excellent performance characteristics. One published design described in Lee, J. J., Livingston S., and Koenig R. A Low-Profile Wide-Band (5:1) Dual-Pol Array, IEEE Antennas and Wireless Propagation Letters Vol. 2, 2003 eliminates the need for electrical continuity between antenna elements.